1st Person,
2d Person, and
3d Person (of Proper Nouns).
This distribution represents properly the Rank or Degree of Persons in the Hierarchy of Personality; the Ego ranking naturally as 'Number One.' Deference or Grace teaches us afterward to defer to the personality of others, and converts our primitive notions of rank into opposites, in a way which is indicated by the honorific use of Thou in addressing the Supreme, etc.
This idea of Personal Rank, the Hierarchical Ascension of Individuality or Personality in Society, abstracted from the particular Individuals, and rendered purely official, becomes nominally a new Part of Speech, and is the whole, substantially, of what we denominate the Pronouns.
The Pronoun, as a Part of Speech, is, therefore, the Analogue, within the Lingual Domain, of The State or the Constitution, governmentally, of Human Society, the ascending and descending rank of individuals in the social organization, the Heraldic Schedule of Man.
Finally we arrive at the consideration of the Casus or Case of Nouns Substantive.
The Accidents of Life or Being, the occasional states of Men or Things, as acting or being acted upon, or simply as related to each other in Space, or otherwise, are here represented. It is this which is meant by Case, from the Latin casus, itself from the Latin cadere, TO FALL, or to FALL OUT or HAPPEN. In the old Grammars, the Cases of the Nouns are denominated Accidents. Ac-cid-ent, is from ad, to, and cadere (cid), TO FALL; and the same root with ob (oc), gives us oc-cas-ion, oc-cas-ionally, etc.
The Accidents of Being are a special kind of Inherence to the Substance of Being; the Relational kind par excellence, as distinguished from the Qualitative kind; which last is denoted by the proper Adjectives. The Oblique Case of a Noun Substantive, whether formed by an Inflexion or by a Preposition, is therefore nothing else than a special kind of Adjective, destitute of the property of Comparison, because it denotes the Accident instead of the Quality of Being, and because Accidents or Relations between Things do not vary by degrees of Intensity as Qualities do.
The above description of the Cases of Nouns applies especially to the Oblique Cases; that is to say, to all except the Nominative Case.
The Nominative Case is itself susceptible of being regarded as an Accident; but its more important office is that of the Subject of the Proposition, which takes it out of the minor category of an accident, or at least subordinates this latter view of its character.
The Accidents of Being in the Universe at large are therefore the analogues of the oblique cases of Nouns Substantive in the Domain of Language; the Nominative Case representing, on the contrary, the central figure in the particular member of discourse, and that which the accidents or falls (casus) are perceived to relate to or affect.